Improvement in burglar-alarms



. L. m JOHNSON.

Burglar-Alarm.

Patented April-20,1875.

T6 W Z M.

THE GRAPHIC C0 PHOT0-UTH.39&41 PARK PLAGEJL! rerea- LAFAYETTE M.JOHNSON, OF FOREST CITY, MISSOURI.

IMPROVEMENT IN BURGLAR-ALARMS.

Specificatirn forming part of Letters Patent No. 1 62,235, dated April20, 1875; application filed January 27, 1875.

To all whom it may concern:

Be it known that I, LAFAYETTE M. J OHN- SON, of Forest City, county ofHolt and State of Missouri, have invented certain new and usefulimprovements in Door-Checks, of which the following is a specification:

My invention relates to that class of doorchecks which are attached tothe door, and have a wheel or roller moving upon the floor; and thenature of my invention consists in combining a burglar-alarm with adoor-check, and also in the construction and combination of parts, aswill be hereinafter more fully set forth.

In order to enable others skilled in the art to which my inventionappertains to make and use the same, I will now proceed to describe itsconstruction and operation, referring to the annexed drawing, whichforms a part of this specification, and in which Figure 1 is a sideelevation of my doorcheck, w1th burglar-alarm attached thereto. Fig. 2is a front View of the same. Fig. 3 is a vertical section of thedoor-check, and Fig. 4 is a perspective view of the burglar-alarm.

A represents a rectangular case of any suitable dimensions, fastened ina vertical position on the inner side of a door. B is the curved orspur-shaped arm, provided with the roller D in its lower forked end. Theupper end of this arm is inserted and slides up and down in the lowerend of the case A. From the upper end of the arm 13 projects a rod, at,having a head, I on its upper end. On this rod is placed a spiralspring, (I. G is the adjustable slide for regulating the pressure of thespring 61, the lower end of said slide being bent at right anglesinward, and forked to straddle the rod a between the head I) and upperend of the spring (1. The lower bent end of the slide 0 is held in aratchet, ac, formed in the case by means of a spring or wedge, asdesired, at any suitable height to regulate the pressure of the roller Don the floor. From the top of the arm B, at the forked end, projects aheaded pin or stud, t upon which is fastened a plate or bar, E, in sucha manner that it can be easily attached or detached at will. On the rearend of the plate E is a post, f, supporting a bell, G, and the front endof the plate is forked with a toothed or corrugated wheel, H, pivotedtherein. Between suitable ears or projections on the plate is pivoted ablock, it, from which projects an arm, m, running along the side of thewheel H, to be operated by means of suitable projections y thereon. Fromthe block it also projects an arm, 12, under the bell G, and this armhas the hammer p attached to it. A spring, t, holds the block, with itsarms, in proper position. As the door opens, the wheel H, running on thefloor, operates, by means of the projections y, the arm on to turn theblock, and as said arm clears each projection the spring it throws theblock h back again, causing the hammer to strike the bell, one blowbeing struck once for each projection y.

The intention is to attach the alarm to the door-check at night, andremove it in the morning. If desired, the alarm may be attached to, orform a bar to be fastened to, the door independent of the door-check.

Having thus fully described my invention, what I claim as new, anddesire to secure by Letters Patent, is

1. In combination with a door-check havin g a yielding arm, with a wheelor roller moving on the floor, a burglar-alarm removably attachedthereto, for the purposes herein set forth.

2. The combination of the plate E, bell G,- wheel H, with projections y,oscillating block h, with arms m a, hammer p, and spring 23,substantially as and for the purposes herein set forth.

In testimony that I claim the foregoing as my invention, I hereuntoaffix my signature this ZOth-day of January, 1875.

L. M. JOHNSON.

Witnesses:

ROBERT STEWART, M. D. BROWN.

